A purely peer-to-peer version of electronic cash would allow online payments to be sent directly from one party to another without going through a financial institution. Digital signatures provide part of the solution, but the main benefits are lost if a trusted third party is still required to prevent double-spending. We propose a solution to the double-spending problem using a peer-to-peer network.
A hierarchy is a system of nested groups. A standard organizational chart is a hierarchy, with employees grouped into business units and departments reporting to a centralized authority. Other kinds of hierarchies include government bureaucracies, biological taxonomies, and a system of menus in a software program. Hierarchies are inherently “top-down,” in that they are designed to enable centralized control from a single, privileged position.
X-ray spectroscopy indicated that the aluminum substitution may be responsible for the durability of the seawater concrete: the ancient material contained a rare hydrothermal mineral, aluminum tobermorite, that is absent in modern concrete formulations. The researchers determined tobermorite has higher stiffness than modern concrete binders and may serve as a model for future concrete strength and durability.
As John Seely Brown and Paul Duguid write in The Social Life of Information, “While it’s clear that self-organization is extraordinarily productive, so too is formal organization. Indeed, the two perform an intricate (and dynamic) balancing act, each compensating for the other’s failings. Self-organization overcomes formal organizing’s rigidity. Formal organization keeps at bay self-organization’s tendency to self-destruct.”